Hi @bchaplin,
I've actually fit two different sizes of Zojurushi thermoses into this mesh pocket, and took pictures of both (but have problems with uploads today). The one in the picture is for tea (16 oz Zojurushi Stainless Steel Travel Mug (with strainer). The other one that I shot (but am having trouble uploading) is the taller 16 oz Stainless Steel Mug with locking cap and drinking spout. The Zojurushi thermoses tend to have smaller diameters, in case people are wondering, and can fit into a Small Cafe Bag. Yes, the 12 oz. sizes will also fit. Weight of Mama Bear is 7 oz. -- less than my Merino jersey, but more than my Merino tee-shirt -- which is about the weight of Baby Bear at 4 oz. Yes, they're made of Parapack. Just note that if you get this for your Little Swift, and are carrying knitting, the mesh on Mama Bear's two front pockets is like the mesh on the 3D Mesh Organizer Cubes and Snake Charmers: it will catch on your wool. The mesh on Baby Bear's back pocket is smooth and stretchy, like the mesh on the Brain Cell.
And yes, you can use Mama Bear in a a Pilot, or in a Co-Pilot if you place it on its side.
moriond